3. Water finds its level

“The natural physics of water is to find and maintain its level. If Earth were a giant sphere tilted, wobbling and hurdling through infinite space then truly flat, consistently level surfaces would not exist here. But since Earth is in fact an extended flat plane, this fundamental physical property of fluids finding and remaining level is consistent with experience and common sense.”

Dubay does not understand gravity or the laws of motion

a.       How can water be level on a sphere?

Gravity exerts a force towards the centre of mass.  So on a spherical Earth, down is always towards the centre of the Earth.  This means that on a spherical Earth, the “level” of the water is its distance from the centre of the Earth.  That distance is the distance that allows the water to be as close as possible to the centre of the Earth.

Here is an interesting video that explains in a little more detail than we need here what sea level is.

b.       Why does the Earth spinning not make the oceans slosh around?

The Earth spins at a constant speed.  There is no rotational acceleration taking place, so the only effect that spinning will have is the Coriolis effect which is enough to create currents in the sea, but not enough to create changes in sea level.

c.       Why does the earth moving around the Sun not make the oceans slosh around?

The Earth is moving through space at a constant speed.  There is no linear acceleration taking place so no force is exerted on the ocean.  Consider driving in a car at 50 miles per hour.  You are not pushed backwards into your seat.  That only happens when you accelerate.  The Earth is not accelerating.

Well actually there is acceleration taking place.  For simplicity I was .... simplifying.

Changing direction is in fact a form of acceleration. Standing on a spinning Earth means you are constantly changing direction and hence experiencing acceleration.  However the force that provides for this acceleration is the Earth's gravity so the only effect that you feel is a tiny reduction in the force of gravity, not some other "unbalancing" force.

Because of the absolutely huge distance that the Earth orbits the Sun, the change in direction and its corresponding acceleration is practically zero, far too small too detect.

If you want to be slightly more technical, this is all down to Newton's second law of motion.

Force = Mass x Acceleration

Using simple maths you can see that if the acceleration is zero or near zero then the force must also be zero or near zero.

 Here is a video showing how small the acceleration is for Pluto orbiting the Sun, but the same applies to the Earth.

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